Method of forming a complex image of a sample

A method for obtaining an image of a sample, the method comprising:

• (a) illuminating the sample using a light source configured to emit a light wave that propagates to the sample;
• (b) acquiring, using an image sensor, a first image of the sample, said first image being formed in a detection plane, the sample being placed between the light source and the image sensor, the first image being representative of an exposure light wave propagating from the sample, to the image sensor, along a first optical path;
• (c) modifying an optical refractive index, between the image sensor and the sample, so as to obtain a variation in the optical path of the exposure light wave;
• (d) acquiring, using the image sensor, a second image of the sample, the second image being formed in the detection plane, the second image being representative of the exposure light wave propagating, from the sample, to the image sensor, along a second optical path, the second optical path corresponding to the first optical path plus the variation in optical path resulting from (c);
• (e) implementing an iterative algorithm comprising the substeps of:
• (ei) forming an initial image, in the detection plane, from a starting image chosen from the first image and the second image;
• (eii) applying a holographic propagation operator to the initial image or to a new complex image formed in the detection plane, resulting from a previous iteration, so as to obtain a reconstructed complex image in a reconstruction plane, a distance between the reconstruction plane and the detection plane corresponding to the variation in optical path obtained in (c), the reconstructed complex image formed in the reconstruction plane having a modulus and a phase defined in each pixel of the reconstructed complex image;
• (eiii) in the reconstruction plane, updating the modulus of the reconstructed complex image formed in the reconstruction plane to form an updated complex image, resulting from (eii), in each of the pixels thereof, depending on a destination image, the destination image being chosen from the first image or the second image, the destination image being different from the starting image chosen in (ei);
• (eiv) applying a holographic propagation operator to the updated complex image of (eiii), to form the new complex image in the detection plane, the new complex image formed in the detection plane having a modulus and a phase defined in each pixel of said image;
• (ev) updating the modulus of the new complex image formed in the detection plane in step (eiv), in each of the pixels thereof, depending on the starting image;
• and
• (evi) reiterating substeps (eii) to (ev) until a criterion for stopping the iterations is met;
• and
• (f) obtaining the image of the sample from one of the new complex image resulting from step (e), the new complex image being formed in the detection plane, or the updated complex image resulting from step (e), the updated complex image being formed in the reconstruction plane.